Minimum power for RTA 12's

laotzu61

I'm new to the forum, altho i've been reading posts here for awhile. I recently picked up a pair of RTA 12's in excellent condition, and i absolutely love 'em. Cleanest, clearest sounding speakers i've heard to date. I am driving them with a kenwood 5600, which is rated at 50 watts per channel rms. My question is this: does anyone know what the minimum power requirement is for these speakers? Is the kenwood a decent match, or do i need to go for a higher rated component? They do sound awesome at this point. Thanks for any input.




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laotzu61

I forgot to ask if anyone is aware of where i may be able to get the optional stands for these. thanks again.

pitdogg2

Well if you like the sound now then you'll love the sound when you feed them some real power. Your not really doing them justice with the power you have now, although that is not to say you can't enjoy them. Feed them good clean power and you'd be amazed at the change. It's easier to blow drivers and tweeters with low power then it is with goobs of current. so just remember that last sentence and you'll be good.

welcome to the club

drumminman

Welcome to CP!

I agree with pitdogg, they can be driven with minimal power, but you won't hear what they can really do until you put at least 150 wpc (preferably high current) behind them.

Can you post pics of your 12's with the grills removed?

drksun

drumminman wrote: »

Welcome to CP!

I agree with pitdogg, they can be driven with minimal power, but you won't hear what they can really do until you put at least 150 wpc (preferably high current) behind them.

Can you post pics of your 12's with the grills removed?

So these speakers aren't ideal for low volume bedroom listening (~50-65dB)?

laotzu61

I would like to post pics if someone will tell me how----computer bozo here. and thanks for the input so far.

soundfreak1

Cant have too much power for those but as mentioned above highcurrent is the ticket for those imho.look for 60+ ampers peek power or more! And they will come alive.if they start jumping off the floor u have too much power. LOL. I drive mine with about 70 ampers and 400 watts, and they all but dance by themselves.

Schurkey

soundfreak1 wrote: »

Cant have too much power for those but as mentioned above highcurrent is the ticket for those imho.look for 60+ ampers peek power or more! And they will come alive.if they start jumping off the floor u have too much power. LOL. I drive mine with about 70 ampers and 400 watts, and they all but dance by themselves.

Since there's NO standard for measuring amplifier amperage, and in my experience amplifier manufacturers who advertise "peak amperage" of some crazy amount will NEVER reveal the test protocol used to generate that insane spec...the spec is COMPLETELY MEANINGLESS. It is all but guaranteed to be an instantaneous peak into a dead short: musically insignificant but makes impressive advertising copy.

50 watts per channel is JUST FINE if it's getting the listener enough volume level.

My garage speakers (1000 sq. ft. room + driveway) are being fed with a "35 watt" amplifier; it's rarely above "3" on the volume dial.

soundfreak1

You are welcome to your opinion schurkey.

FastGame

I power my RTA 12b's with a QSC 1300, 600w per channel @4ohm. When the tweeters start to glow and glass breaks I know it's time to turn things off :loneranger:

Schurkey

soundfreak1 wrote: »

You are welcome to your opinion schurkey.

soundfreak1 wrote: »

I drive mine with about 70 ampers and 400 watts

So tell me...WHAT IS THE TEST PROTOCOL that generates 70 amperes from your amplifier? HOW LONG will the amp sustain 70 amps? What load (8-ohm, 4-ohm, 1-ohm???) will it drive while generating 70 amps? HOW does that test protocol relate to a music signal applied to a typical speaker load?

soundfreak1

Schurkey dont crap on this guys thread! If you want to argue that crap atart your own thread. I have no intrest in mental masterbation on someone elses thread.

Schurkey

soundfreak1 wrote: »

Schurkey dont crap on this guys thread! If you want to argue that crap atart your own thread. I have no intrest in mental masterbation on someone elses thread.

Yep, that's what I figured. You have NO IDEA how they managed to come up with a "70 amp" spec. You were lied to, by a corrupt and unethical manufacturer, and the Federal Trade Commission can't be bothered to assist the consumer when a corporation abuses the public.

Fact is, Polk speakers were advertised as "easy to drive" and are reasonably sensitive (efficient). They don't require monster amplifiers; although when modified they respond very nicely to high-end components up-stream. Until they're modified with low-resistance inductors and such, they don't require massive amounts of current. (Unlike, for example, the Apogee Scintilla, which (I'm told) had a sub-one-ohm impedance at a certain point in the frequency range.)

If an amp is rated for a nominal 4-ohm load, it'll be fine. If it's got enough power to satisfy the volume requirements of the original poster, it's fine. I'm not a bit surprised that the original poster can use a "50 watt" receiver and get musically-satisfying sound.

At the point when the volume increases, he'll likely need a more-powerful amp. If he has both hearing acuity and "music acuity" he may appreciate a higher-quality amp. That amp may or may not have more power than his present amp.

soundfreak1

Laotzu61 if your speakers are the original rta 12's i believe they do not have risers like the b's and c's do, if so ( as i have been told) you want tweets aprox. ear level i dont know if that is a absolute rule just what i go by. I plan to add 2" to my risers bringing them to 4" off floor. But expieriment to see how tjey sound at various heights before u spend money on stands. If you feel u need them and you are handy you can make them or buy them if necessary.or it would be easy to put "riaers" like the b modles have without being a carpenter.as far as posring picts goes right next to the "post quick reply" button it says. "go advanced" push that button and scroll down to the manage atachments button hit that and than follow the instructions to upliad photos. Hope this helps.

pitdogg2

aren't the originals also left and right ? Or am I thinking of another model?

soundfreak1

I think all the RTA 12's are. At least i know the b&c's are sure.

laotzu61

first off, i really appreciate ALL the input and information i've been getting from you. that said, i don't see a problem with "creative disagreement, but wouldn't like to see an arguement between anyone--we all share a common bond. anyway, the speakers are 39 1/2" high with a couple felt shims (spelling?) underneath. they are at ear level when i'm in my "sitting" chair. also, i live in a BIG older house (1921) in which the living room and dinning room are connected into one big space. hardwood floors with 2 8x12 area rugs. depending on what i'm playing, 1/4 volume on the 5600 blows me away. right now i am playing "music of the spheres", mike oldfield, and it's loud and i'm below 1'4 volume. if i'm playing blues or jazz, i get close to 1/4. thanks again for all the information. i just love these speakers!!! btw, i would like to get a phase linear amp and preamp or a big kenwood down the road.

lanchile

laotzu61 wrote: »

I'm new to the forum, altho i've been reading posts here for awhile. I recently picked up a pair of RTA 12's in excellent condition, and i absolutely love 'em. Cleanest, clearest sounding speakers i've heard to date. I am driving them with a kenwood 5600, which is rated at 50 watts per channel rms. My question is this: does anyone know what the minimum power requirement is for these speakers? Is the kenwood a decent match, or do i need to go for a higher rated component? They do sound awesome at this point. Thanks for any input.

i

Hi, 50 watts R.M.S is not so little!!! many people think more power= better sound...well that is not so true (there are more factors that contribute to better sound)! I would fallow the posts from Schurkey, I have build many diy amps and the one I build now it is just around 70 watts R.M.S per channel and I do not see the need for more power, I use Polk RTi A1. Also you have to see how efficient your speakers are. the higher the S.P.l the less power you will need to push at high volume. I would use that amp with not worries.

drumminman

The original RTA 12's have a different Xover design and are not left and right speakers. The B's and C's are, though. On these two later versions the MW's in each cabinet cover different parts of the frequency range with some overlap, though I can't remember the specifics right now.

When I put my C's back into play last year I inadvertantly reversed the cabinets. Terrible stereo image, and just sounded bad. When I got them set up properly it made a huge difference.

Re: the power to drive these, yes they can be driven by modestly powered amps/AVR's. But they respond quite well to higher power/higher current amplifiers. I recently switched amps from a Carver TFM 42 to a new Odyssey Dual Mono, and the improvement was easy to hear, even at modest volumes. Just depends on how much you want to spend and the level of sound quality you're trying to achieve.

laotzu61

i believe i have the original rta 12's. they do have sequential serial numbers, for what it's worth. there are a pair of kenwood monoblocks for sale on the site, and if i hadn't gotten laid off 2 weeks ago, i would have jumped all over them.

drumminman

When the time is right and you can get a separate power amp you'll be very pleased.

laotzu61

i just looked at an original sales brochure i had downloaded some time ago on rta 12b's. i took the grill covers off mine, and they look exactly the same as the 12b's pictured. how do i know which rta's i have? also, it states that they are 4 ohm speakers, which means the kenwood 5600 i'm driving them with rated at 50 watts rms per channel would translate into 100 watts per with these speakers; correct? thanks yet again.

Schurkey

laotzu61 wrote: »

it states that they are 4 ohm speakers, which means the kenwood 5600 i'm driving them with rated at 50 watts rms per channel would translate into 100 watts per with these speakers; correct? thanks yet again.

Nope. SOME amplifiers will double the 8-ohm wattage spec into a 4-ohm load. Not common, usually expensive; typically done by slightly under-rating the 8-ohm spec.

First Guess: Your Kenwood is current-limited to the point that the 4-ohm spec will be about 130--150 percent of the 8-ohm spec. Your "50 watt" receiver at 8 ohms may be rated for 65--75 watts at 4 ohms. An online search for information about the unit may turn up a spec sheet. All I remember seeing when I did a quick search was an eBay auction for that model receiver.

Schurkey

laotzu61 wrote: »

i would like to get a phase linear amp and preamp or a big kenwood down the road.

As long as you're aware that old amplifiers have the SAME problem with capacitors that old speaker crossovers do.

Electrolytic caps aren't all that wonderful when they're NEW, and they degrade fairly quickly. TOP QUALITY electrolytics seem to have about a twenty-year service life; and the caps in those old amps aren't likely to be top-quality.

I remember Flame Linear amplifiers from the roller-skating rink I attended when in "college". Seemed so wonderful then, but they're totally out-classed by newer amps; including those from the same engineer--Bob Carver.

I have a similar affinity for certain older JVC receivers as you do for Kenwood. Same story--they were fine in their day; after thirty-something years of capacitor degradation, they're unlikely to meet their "as new" specifications. Even so, I have a trio of JVCs doing occasional duty around my house and garage; they sound fine at least at lower volume (I don't push them very hard, the least-powerful one gets the most use, 35 watts and never beyond "4" on the volume knob. More usually "1" or "2".) Someday, I'm going to freshen-up the power supply caps on all of them--but I've got too many other projects being ignored to even put that on a time table.

My old receivers work, sound reasonably good, and still provide utility in "the real world". One of 'em has a tendency to shut down unpredictably, though.

drumminman

laotzu61 wrote: »

i just looked at an original sales brochure i had downloaded some time ago on rta 12b's. i took the grill covers off mine, and they look exactly the same as the 12b's pictured. how do i know which rta's i have? also, it states that they are 4 ohm speakers, which means the kenwood 5600 i'm driving them with rated at 50 watts rms per channel would translate into 100 watts per with these speakers; correct? thanks yet again.

The visual differences are not that apparent when looking at the front baffle.

Do your cabinets have pedestals on the bottom? IF not they are orginal RTA 12's (not B's or C's), and they are not mirror imaged, i.e. a specific L and R cabinet.

If they have pedestals get your read on here: http://www.polkaudio.com/forums/showthread.php?119563-left-right-on-rta-12b-s&highlight=RTA12+speakers

More info on ID'ing these here - mine are like the ones in the thread with RTA 12B printed on the pcb, A manual that came with them that states RTA 12C (bought 'em new) and the fuse instead of the polyswitch (see post #7):
http://www.polkaudio.com/forums/showthread.php?58029-RTA12-Identification&highlight=RTA12+speakers

One issue with this is some late model B's had the same components as early model C's, due to Polk using up on hand components. Early C's (like mine) used the SL1000 tweeter, while later ones used the SL2000. Not sure which MW's.

Found some pics posted by another member of his 12C's here: https://plus.google.com/photos/117101773389589754809/albums/5132686316229005185?banner=pwa

laotzu61

ok. the speakers have a square wood base underneath about 1 1/2" high; no pedestal as i've seen on some pics. the tweeter/crossover circuit board has #22 10214 on what i'm using as the left speaker, and #22 10213 on what i'm using as the right speaker. the left coil on each is mounted parallel to the length of the board ( - ) while the right is mounted vertical. i'm just stating this as a means of identification as to what i might have. also, should i be looking at switching left and right speakers because of the numbers on the circuit boards, or am i over complicating this? (wouldn't be the first time!!) i obviously have a lot to leard.

pitdogg2

Calling Keith (Geppy1) come in keith....

OP get to 10 post and PM Geppy he is our resident RTA12 pro he has it down to a science. He went into depth and did a ton of research on all the different versions and the in-between versions.


When they are left and right i was under the impression that the outer MW carried the low freq and overlapped to the upper region.

laotzu61

there is a guy in the classifieds selling a pair that are exactly what mine look like, so they muct be RTA 12's. so, is there a left and a right for there, or no??

FastGame

man-o-man I 'm confused on what speakers I have....I thought or think they're 12b's but now they might be crossbred 12b/c's with some regular 12 thrown in :eek:

drumminman

laotzu61 wrote: »

there is a guy in the classifieds selling a pair that are exactly what mine look like, so they muct be RTA 12's. so, is there a left and a right for there, or no??

No left and right for 12's, only for B's and C's.

Put up some pics - that'll help us ID them.

laotzu61

if someone would please explain how i post pics, i will do so. and thanks.